After knitting most of the front of a jumper, you've finally reached the neckline, and, as many beginner knitters have found, this is where the confusion starts. The method used to shape a neckline depends on the kind of neckline required. Some styles are knitted simultaneously on one pair of needles, while others require the knitter to knit each side of the neckline separately. Every style is shaped by decreasing the stitches along the edges of the neckline as the knitter knits towards the jumper shoulder. Most patterns instruct to begin by casting off stitches in the centre of the row, then decreasing by one stitch on regular or set rows.
Knit along the row to one stitch before the centre, with the right side of the jumper facing you. Cast off a stitch by knitting one stitch, then pulling the adjacent stitch on your right hand needle over it and off the needle. Repeat once. Knit to the end of the row. Work on one side of the neck at a time.
Decrease stitches on one side of the centre as you knit towards shoulder, either by knitting two stitches together, or by slipping a stitch from the left hand needle to the right, knitting a stitch, then lifting the slipped stitch over the knitted stitch and off the right hand needle. Decrease stitches evenly, reducing one stitch per set number of rows to achieve the desired depth.
Stop decreasing stitches 2.5 cm (1 inch) below the shoulder edge. Continue knitting to the shoulder, then cast off all stitches. Join the yarn to the centre of the fabric and knit the other side of the neckline, decreasing from the centre once more.
Cast off the required number of stitches in the middle of the row to give the desired width at the bottom of the neckline. Continue knitting to the end of the row.
Knit both sides of the neckline at the same time. Cast off two stitches on either side of the neckline, then decrease one stitch on either side every other row. Continue for five rows, or until you reach the required depth of shaping.
Knit without further decreasing to the top of the shoulders, then cast off all stitches.
The amount of stitches and frequency of stitch reduction depends on the stitch-to-fabric ratio and the size of neckline required. For example, to create a 15 cm (6 inches) wide v-neckline in fabric that's 40 cm (16 inches) wide and has 70 stitches in a row, divide 40 by 70, then multiply by 15, which gives 26.25. You need to decrease 26 stitches, or 13 on each side of the neck. To calculate how often you must decrease stitches, count how many rows on your fabric make up the neckline depth desired. To decrease 13 stitches evenly 15 cm (6 inches) deep, in fabric that has 26 rows every 15 cm (6 inches), you must decrease one stitch every other row.
Don't decrease the stitches at the very end of a row as this gives a rough, uneven finish. Decrease the two stitches just before instead.